does any one know if the helix 9 mega chirp transducer(xm 9 20 msi t)can be upgraded to a hi diff.transom mount transducer and what would the model # be .if so,what would the price be?I'm looking to buy the mega model and trade in td for hi diff.thanks

does any one know if the helix 9 mega chirp transducer(xm 9 20 msi t)can be upgraded to a hi diff.transom mount transducer and what would the model # be .if so,what would the price be?I'm looking to buy the mega model and trade in td for hi diff.thanks